Normal maps baking crashes blender 2.90. Exact same blender file as in blender 2.83 where bake doesn't crash
my solution
install blender v2.91 experimental build as of 15_09_2020
installed not on c drive
did not take set up from v2.90

additionally
make sure hires and low rez have render flag on if off fails
set bake to an actual folder path not c\tmp prefarably not on c drive
save as rgb 16 bit no alpha
set samples to 1 1
make sure bake extrusion big size here 2m, but if overlapping geo smaller size.
create new texture for normal map alpha off 32 bit on,will save as 16 bit later
assign mat to lowres, then image map load your new empty normal map button left
set to non colour
DO NOT  link up node till baked
sel hirez geo then ctrl sel lowres geo, sel image map
BAKE used def tile size 32 32https://www.flickr.com/photos/93465359@N03/50343650117